Thiono-thiochroman and -dihydrobenzothiophene compounds as herbicidal agents

ABSTRACT

The present invention provides a compound of formula I:                    
     wherein X is O or S(O) n ; n is zero, 1 or 2; and Y is CR 7 R 8 , CHOR 9 , C(OR 9 ) 2 , C═NOR 10  or C═NNR 20 R 21 . 
     Compounds of formula I are useful as herbicidal agents, particularly as agents for the control of undesirable plant species in the presence of a cereal crop.

This application claims priority from provisional application Ser. No.60/161,154 filed Oct. 22, 1999.

BACKGROUND OF THE INVENTION

Weeds cause tremendous global economic losses by reducing crop yieldsand lower crop quality. Worldwide agronomic crops must compete withhundreds of weed species. Herbicides, used to combat these weed speciesare now standard technology on farms and ranches. The proper agronomicuse of herbicides results in increased crop yields and quality and,concomitantly, increases production and harvesting efficiency.

In spite of the commercial herbicides available, damage to crops causedby weeds still occurs. In addition, often herbicides do not provide asufficient margin of safety for the crop, thus damaging the crop as wellas the weeds. Accordingly, there is an ongoing need to create morecrop-selective as well as more effective herbicidal agents.

Thiochroman and dihydrobenzothiophene (DHBT) herbicidal agents aredescribed in U.S. Pat. No. 5,607,898 and WO 97/08164. However, none ofthe compounds described therein contain a thiono moiety.

It is therefore an object of the present invention to providethiono-thiochroman and thiono-dihydrobenzothiophene compounds whichdemonstrate herbicidal activity in conjunction with crop safety.

SUMMARY OF THE INVENTION

The present invention provides a herbicidal compound of formula I

wherein m is zero or 1;

R₁, R₂, R₃ and R₄ are each, independently, H, C₁-C₄ alkyl, C₁-C₄haloalkyl or C₂-C₄ alkoxyalkyl;

R₅ is C₁-C₃ alkyl, C₂-C₄ alkenyl, or C₂-C₄ haloalkyl;

R₆ is H, halogen, CN, NO₂, C₁-C₄ alkyl, C₂-C₄ alkenyl, or C₂-C₄alkoxyalkyl.

X is O or S(O)_(n);

n is zero, 1 or 2;

Y is CR₇R₈, CHOR₉, C(OR₉)₂, C═NOR₁₀, C═O or C═NNR₂₀R₂₁;

R₇ is H, C₁-C₄ alkyl or C₁-C₄ haloalkyl;

R₈ is H, C₁-C₄ alkyl or C₂-C₄ alkenyl or C₂-C₄ alkenyl;

R₉ and R₁₀ are each, independently H, C₁-C₆ alkyl optionally substitutedwith one or more halogen, C₁-C₄ alkoxy, C₂-C₆ alkenyl, C₂-C₆ alkynyl,C₁-C₆ haloalkyl or C₃-C₆ cycloalkyl groups, or when two R₉ groups arepresent they may be taken together with the atoms to which they areattached to form a five- or six-membered ring;

Q is H, SO₂R₁₁, COR₁₂, CO₂R₁₃, P(O) (OR₁₄)₂ or C₁-C₄ alkyl optionallysubstituted with COR₁₅, CO₂R₁₆, P(O) (OR₁₇)₂ or phenyl optionallysubstituted with one to three halogen, NO₂, C₁-C₄ alkyl, C₁-C₄ alkoxy orC₁-C₄ haloalkyl groups;

R₁₁, R₁₃, R₁₄, and R₁₇ are each independently C₁-C₈ alkyl, C₃-C₈cycloalkyl, or phenyl, optionally substituted with one to three halogen,nitro, C₁-C₄ alkyl, C₁-C₄ alkoxy or C₁-C₄ haloalkyl groups;

R₁₂ and R₁₅ are each independently H, NR₁₈R₁₉, C₁-C₈ alkyl, C₃-C₈cycloalkyl or phenyl optionally substituted with one to three halogen,NO₂, C₁-C₄ alkyl, C₁-C₄ alkoxy or C₁-C₄ haloalkyl groups;

R₁₆ is H, C₁-C₈ alkyl, C₃-C₈ cycloalkyl or phenyl optionally substitutedwith one to three halogen, NO₂, C₁-C₄ alkyl, C₁-C₄ alkoxy or C₁-C₄haloalkyl groups;

R₁₈ and R₁₉ are each independently H or C₁-C₆ alkyl;

R₂₀ and R₂₁ are each independently H or C₁-C₆ alkyl or R₂₀ and R₂₁ maybe taken together with the atom to which they are attached to form afive- or six-membered ring;

Z is H, halogen, C₁-C₄ alkyl, C₁-C₄ haloalkyl, C₂-C₄ alkoxyalkyl, C₁-C₄alkoxy or C₁-C₄ haloalkoxy; and

p is zero, 1, 2, or 3; or

the agriculturally acceptable salts thereof.

Also provided are herbicidal compositions and methods and a process forthe preparation of the Formula I compound.

DETAILED DESCRIPTION OF THE INVENTION

The term safety or selectivity in weed science refers to thecharacteristic by which undesirable species of plants (weeds) are killedor seriously injured in the presence of desirable plant species (crops)without concomitant injury of the desired plant species. The use ofherbicides frequently causes a varying degree of crop injury. Such cropdamage is a problem that generates a continuous need for more selectiveherbicides worldwide. This is especially true of crops such as cerealswhich are often unacceptably damaged by herbicides designed to protectsaid crops against invasive weeds.

Surprisingly, it has now been found that the formula I compounds of theinvention demonstrate good herbicidal efficacy against undesirable plantspecies along with enhanced crop selectivity. In particular, the formulaI compounds of this invention are surprisingly safe in cereal crops suchas corn, wheat, rice, or the like, preferably corn.

Compounds of the invention have the structural formula I

wherein R₁, R₂, R₃, R₄, R₅, R₆, Q, X, Y, Z, m and p are describedhereinabove.

The term halogen as used in the specification and claims designateschlorine, fluorine, bromine or iodine. The term haloalkyl designates analkyl group, C_(n)H_(2n+1) which may contain from one halogen atom to2n+1 halogen atoms. Similarly, the term haloalkoxy designates aOC_(n)H_(2n+1) group which may contain from one to 2n+1 halogen atoms.Haloalkenyl designates an alkenyl group C_(n)H_(2n) which may containfrom one to 2n halogen atoms. In each instance the halogen atoms may bethe same or different.

The formula I compounds of the invention include all stereoisomeric andregioisomeric embodiments.

The agriculturally acceptable salts of formula I include salts such asalkali metal, e.g. lithium, sodium or potassium; alkaline-earth metal,e.g. calcium or magnesium; ammonium or amine, e.g. diethanolamine,triethanolamine, octylamine, morpholine, dioctylmethylamine or any ofthe conventional salts suitable for use in standard agriculturalpractice.

Preferred compounds of the present invention are those formula Icompounds wherein X is SO₂; Q is H; and Y is CR₇R₈, CHOR₉, C(OR₉)₂ orC═NOR₁₀.

Compounds of formula I, wherein Q is hydrogen, may be prepared from thecorresponding ketone by treatment of said ketone with Lawesson's Reagentin the presence of a solvent, preferably an inert solvent such asdimethoxyethane. The reaction is shown below in Flow Diagram I.

Flow Diagram I

Lawesson's reagent may be represented by the structure shown below andis available commercially.

Compounds of formula I in which Q is SO₂R₁₁ may be prepared by treatingthe formula I compound wherein Q is hydrogen with a suitable sulfonatingagent,R₁₁SO₂halide, in the presence of a base, preferably potassiumcarbonate. The reaction may be conveniently carried out in a two-phasesolvent system in the presence of a phase-transfer catalyst such asbenzyltriethylammonium chloride (BTEAC). The reaction is shown in FlowDiagram II, wherein the sulfonyl halide is a sulfonyl chloride.

Flow Diagram II

Compounds of formula I wherein Q is is other than H or SO₂R₁₁ may beprepared in a manner similar to that described in U.S. Pat. No.5,607,898 or in WO 97/08164.

Advantageously, it has now been found that the formula I compounds ofthe invention are particularly useful for the selective control ofundesirable plant species in the presence of crop plants, seeds or otherpropagating organs. In particular, the compounds of this invention areselective in cereal crops such as corn, wheat, rice or the like,preferably corn.

In actual practice, the compounds of the invention may be applied to thefoliage of undesirable plants or to the soil or water containing seedsor other propagating organs thereof, preferably to the foliage, in theform of a solid or liquid herbicidal composition. Said composition maytake the form of an emulsifiable concentrate, a concentrated emulsion, awettable powder, a soluble granule, a suspension concentrate, a flowableconcentrate or any convenient conventional form useful for herbicideapplication.

The composition of the invention comprises an agronomically acceptableinert solid or liquid carrier and a herbicidally effective amount of acompound of formula I. The herbicidally effective amount of the formulaI compound may vary according to the prevailing conditions such as weedpressure, crop species, application timing, form of application, soilconditions, weather conditions or the like. In general, hebicidallyeffective amounts may be obtained when the composition of the inventionis applied at rates of about 0.001 kg/ha to 10.0 kg/ha, preferably about0.003 to 0.50 kg/ha, more preferably about 0.006 to 0.20 kg/ha.

The composition of the invention may be applied in combination withother herbicides such as dinitroanilines, for example trifluralin,pendimethalin or the like, preferably pendimethalin; triazines, forexample atrazine, cyanazine, metribuzin or the like; AHAS inhibitors forexample imidazolinones, sulfonyl ureas or the like; protox inhibitors;or any of the commonly employed, commercially available herbicidalagents. Said combination may be applied sequentially or concurrently asa tank-mix or co-formulation. Compositions of the invention embracecompounds of formula I alone or in combination with a second herbicideas active ingredient, preferably pendimethalin.

In order to further illustrate the invention, the following examples areset forth below. The terms ¹HNMR, ¹³CNMR designate proton and carbonNMR, respectively and the terms IR and MS designate infraredspectrometry and mass spectroscopy, respectively. The terms HPLC and TLCdesignate high performance liquid chromatography and thin layerchromatography, respectively. Unless otherwise stated, all parts areparts by weight.

EXAMPLE 1 Preparation of6-[(1-Ethyl-5-hydroxypyrazol-4-yl)thicarbonyl]-5-methylthiochroman-4-one(E) -O-Methyloxime, 1,1-Dioxide

A stirred suspension of the 4-(O-methyloxime) of6-[(1-ethyl-5-hydroxypyrazol-4-yl)carbonyl]-5-methyl-thiochroman-4-one1,1-dioxide (50.0 g, 0.132 mol) in 500 mL dimethoxyethane (DME), undernitrogen, is treated with Lawesson's Reagent (53.6 g, 0.132 mol), heatedat 65-70° or a period of 15 h [during this period, additional Lawesson'sReagent is added (39.5 g, 0.098 mol)], cooled to room temperature andfiltered. The filtrate is concentrated in vacuo to give a syrup. Thesyrup is diluted with diethyl ether, washed sequentially with water andbrine, dried over sodium sulfate and concentrated in vacuo to give asecond syrup. The second syrup is dissolved in methylene chloride andchromatographed on silica gel using a gradient elution (CH₂Cl₂/Et₂O:100/0 to 90/10) to give the title compound as a golden-yellow solid, mp92°-97° C., 24.1 g, (46.1% yield), identified by IR, ¹HNMR, ¹³CNMR andMS analyses. Quantitative NMR analysis indicates a product purity of97.7% with the ratio of oxime isomers (E/Z: 95/5) unchanged

EXAMPLES 2-4 Preparation of Thiono-thiochroman and -Dihydrobenzo [b]thiohene Compounds

Using essentially the same procedure described in Example 1 (andemploying the appropriate keto substrate, the compounds shown in Table Iare obtained.

TABLE I

Ex. mp No. R₆ R₇ R₈ Zp m n ° C. 2 C₂H₅ CH₃ CH₃ 5,8-di-CH₃ 1 2 — 3 CH₃CH₃ CH₃ 4-CH₃ 0 2 214-216 4 C₂H₅ CH₃ CH₃ 4-CH₃ 0 2 136-134

EXAMPLE 5 Preparation of6-{[1-Ethyl-5-sulfonyloxy)pyrazol-4-yl]thiocarbonyl}-5-methylthiochroman-4-one(E)-O-Methyloxime, 1,1-Dioxide

A solution of6-[(1-ethyl-5-hydroxypyrazol-4-yl)thiocarbonyl]-5-methylthiochroman-4-one(E)-O-methyloxime, 1,1-dioxide (0.81 g, 2.1 mmol) in methylene chlorideis treated with 0.34 g potassium carbonate, 0.024 gbenzyltriethylammonium chloride, water and n-propylsulfonyl chloride(0.44 g, 3.1 mmol), stirred at room temperature for 18 hr and dilutedwith methylene chloride and water. The phases are separated and theaqueous phase is washed sequentially with methylene chloride. Thecombined organic phases are washed with water, 1% HCl , water, andbrine, dried over anhydrous magnesium sulfate and concentrated in vacuoto give a dark brown syrup. The syrup is purified by silica gelchromatography, using gradient elution (methylene chloride/ether:100/0-95/5) to give the title product as a yellow-brown solid, mp95-105° C., (54% yield) characterized by ¹³CNMR, ¹HNMR and mass spectralanalyses.

EXAMPLE 6 Postemergence Herbicidal Evaluation Of Test Compounds

The herbicidal activity of the compounds of the present invention isevaluated by the following tests

Seedling plants are grown in jiffy flats for about two weeks. The testcompounds are dispersed in 80/20 (v/v) acetone/water mixtures containing1.0% SUN-IT® II, a methylated seed oil, in sufficient quantities toprovide the equivalent of about 0.006 kg/ha to 0.800 kg/ha of activecompound when applied to the plants through a spray nozzle operating at40 psi for a predetermined time. After spraying, the plants are placedon greenhouse benches and are cared for in accordance with conventionalgreenhouse procedures. Approximately two—three weeks after treatment,the seedling plants are examined and rated according to the ratingsystem set forth below. Where more than one test is involved for a givencompound, the data are averaged. The results are shown in Table II.

HERBICIDE RATING SCALE

% Control as compared to Rating the untreated check 9 100 8 91-99 780-90 6 65-79 5 45-64 4 30-44 3 16-29 2  6-15 1 1-5 0  0

PLANT SPECIES EMPLOYED

Header Abbr. Common Name Scientific Name ABUTH Velvetleaf Abutilontheophrasti, Medic. AMBEL Ragweed, Common Ambrosia artemisifolia, L.CASOB Sickelpod Cassia Obtusifolia, L. CHEAL Lambsquarters, Chenopodiumalbum, L. Common IPOSS Morningglory, spp. Ipomoea spp. IPOHEMorningglory, Ipomoea hederacea, (L) Jacq. Ivyleaf ECHCG BarnyardgrassEchinochloa crus-galli, (L.) Beau PANDI Panicum, Fall Panicumdichotomiflorum, Michx. SETVI Foxtail, Green Setaria viridis, (L.) BeauZEAMX Corn, Field Zea mays, L.

TABLE II POSTEMERGENCE HERBICIDAL EVALUATION Example Rate Number (kg/ha)ABUTH AMBEL IPOHE ECHCG PANDI SETVI ZEAMX 1 0.100 8.0 8.4 3.0 7.8 6.59.0 3.0 0.050 7.6 8.2 2.0 8.0 6.3 8.5 1.2 2 0.100 9.0 9.0 4.0 9.0 4.09.0 1.0 0.050 9.0 6.0 2.0 5.0 5.0 9.0 0.0 3 0.100 8.0 8.0 9.0 8.0 8.03.0 0.050 9.0 9.0 7.0 7.0 8.0 2.0 4 0.100 7.0 8.0 4.0 8.0 9.0 7.0 2.00.050 4.0 8.0 4.0 8.0 3.0 4.0 0.0 5 0.100 3.0 0.050 0.0

EXAMPLE 7 Preemergence Herbicidal Evaluation of Test Compounds

In these tests, seeds of a variety of monocotyledonous anddicotyledonous plants are separately mixed with potting soil and plantedon top of approximately one inch of soil in separate pint cups. Afterplanting, the cups are sprayed with the selected aqueous acetonesolution containing test compound in sufficient quantity to provide theequivalent of about 0.0125 to 0.800 kg per hectare of test compound percup. The treated cups are then placed on greenhouse benches, watered andcared for in accordance with conventional greenhouse procedures.Approximately two—four weeks after treatment, the tests are terminatedand each cup is examined and rated according to the rating systemprovided in Example 6. The results obtained are shown in Table III.

TABLE III PREEMERGENCE HERBICIDAL EVALUATION Example Rate Number (kg/ha)ABUTH AMBEL IPOHE ECHCG PANDI SETVI ZEAMX 1 0.100 9.0 8.8 6.0 8.3 8.58.4 0.8 0.050 7.3 8.5 2.5 5.8 8.0 6.6 0.0 2 0.100 9.0 3.0 0.0 3.0 7.05.0 0.0 0.050 3.0 2.0 0.0 0.0 5.0 4.0 0.0 3 0.100 9.0 7.0 2.0 8.5 8.07.0 0.0 0.050 8.0 5.5 2.0 7.0 6.5 5.0 0.0 4 0.100 9.0 9.0 1.0 9.0 7.03.0 0.0 0.050 6.0 2.0 1.0 2.0 2.0 3.0 0.0 5 0.100 9.0 9.0 6.0 7.0 6.00.0 0.050 9.0 7.0 6.0 7.0 6.0 0.0

I claim:
 1. A compound of formula I

wherein m is zero or 1; R₁, R₂, R₃ and R₄ are each independently, H,C₁-C₄ alkyl, C₁-C₄ haloalkyl or C₂-C₄ alkoxyalkyl; R₅ is C₁-C₃ alkyl,C₂-C₄ alkenyl, or C₂-C₄ haloalkyl; R₆is H, halogen, CN, NO₂, C₁-C₄alkyl, C₂-C₄ alkenyl, or C₂-C₄alkoxyalkyl; X is O or S(O)_(n); n iszero, 1 or 2; Y is CR₇R₈, CHOR₉, C(OR₉)₂, C═NOR₁₀ or C═NNR₂₀R₂₁; R₇ isH, C₁-C₄ alkyl or C₁-C₄ haloalkyl; R₈ is H, C₁-C₄ alkyl or C₂-C₄ alkenylor C₂-C₄ alkynyl; R₉ and R₁₀ are each, independently H or C₁-C₆ alkyloptionally substituted with one or more halogen, C₁-C₄ alkoxy, C₂-C₆alkenyl, C₂-C₆ alkynyl, C₁-C₆ haloalkyl or C₃-C₆ cycloalkyl groups; Q isH, SO₂R₁₁, COR₁₂, CO₂R₁₃, P(O)(OR₁₄)₂ or C₁-C₄ alkyl optionallysubstitute COR₁₅, CO₂R₁₆, P(O)(OR₁₇)₂ or phenyl optionally substitutedwith one to three halogen, NO₂, C₁-C₄ alkyl, C₁-C₄ alkoxy or C₁-C₄haloalkyl groups; R₁₁, R₁₃, R₁₄, and R₁₇ are each independently C₁-C₈alkyl, C₃-C₈ cycloalkyl, or phenyl, optionally substituted with one tothree halogen, nitro, C₁-C₄ alkyl, C₁-C₄ alkoxy or C₁-C₄ haloalkylgroups; R₁₂ and R₁₅ are each independently H, NR₁₈R₁₉, C₁-C₈ alkyl,C₃-C₈ cycloalkyl or phenyl optionally substituted with one to threehalogen, NO₂, C₁-C₄ alkyl, C₁-C₄ alkoxy or C₁-C₄ haloalkyl groups; R₁₆is H, C₁-C₈ alkyl, C₃-C₈ cycloalkyl or phenyl optionally substitutedwith one to three halogen, NO₂, C₁-C₄ alkyl, C₁-C₄ alkoxy or C₁-C₄haloalkyl groups; R₁₈ to R₂₁ are each independently H or C₁-C₆ alkyl; Zis H, halogen, C₁-C₄ alkyl, C₁-C₄ haloalkyl, C₂-C₄ alkoxyalkyl, C₁-C₄alkoxy or C₁-C₄ haloalkoxy; and p is zero, 1,2, or 3; or theagriculturally acceptable salts thereof.
 2. The compound according toclaim 1 wherein X is SO₂; Q is H; and Y is CR₇R₈, CHOR₉, C(OR₉)₂, orC═NOR₁₀.
 3. The compound according to claim 2 wherein R₇ and R₈ are eachindependently C₁-C₄ alkyl.
 4. The compound according to claim 2 whereinR₁₀ is C₁-C₄ alkyl.
 5. The compound according to claim 46-[(1-ethyl-5-hydroxypyrazol-4-yl)thiocarbonyl]-5-methylthiochroman-4-one-O-methyloxime,1,1-dioxide.
 6. A method for the control of undesirable plants whichcomprises applying to the foliage of said plants or to the soil or watercontaining seeds or other propagating organs thereof a herbicidallyeffective amount of a compound of formula I

wherein R₁, R₂, R₃, R₄, R₅, R₆, Q. X, Y, Z, m and p are as described inclaim
 1. 7. The method according to claim 6 wherein the formula Icompound is applied to the foliage of said plants.
 8. The methodaccording to claim 6 wherein said undesirable plants are in the presenceof a crop.
 9. The method according to claim 8 wherein said crop is acereal crop.
 10. The method according to claim 9 wherein said crop iscorn.
 11. The method according to claim 6 having a formula I compoundwherein X is SO₂; Q is H; and Y is CR₇R₈, CHOR₉, C(OR₉)₂, or C═NOR₁₀.12. The method according to claim 11 wherein R₇ and R₈ are eachindependently C₁-C₄ alkyl.
 13. The method according to claim 11 whereinR₁₀ is C₁-C₄ alkyl.
 14. The method according to claim 13 wherein theformula I compound is6-[(1-ethyl-5-hydroxypyrazol-4-yl)thiocarbonyl]-5-methylthiochroman-4-one,O-methyloxime, 1,1-dioxide.
 15. The method according to claim 6 whereinthe formula I compound is applied at a rate of about 0.001 kg/ha to 10.0kg/ha.
 16. The method according to claim 15 wherein the formula Icompound is applied at a rate of about 0.006 kg/ha to 1.0 kg/ha.
 17. Aherbicidal composition which comprises an agriculturally acceptablecarrier and a herbicidally effective amount of a compound of formula I

wherein R₁, R₂, R₃, R₄, R₅, R₆, Q, X, Y, Z, m and p are as described inclaim
 1. 18. The composition according to claim 17 having a formula Icompound wherein X is SO₂; Q is H; and Y is CR₇R₈, CHOR₉, C(OR₉)₂, orC═NOR₁₀.
 19. The composition according to claim 18 wherein R₁₀ is C₁-C₄alkyl.
 20. A process for the preparation of a compound of formula Ia

wherein m is zero or 1; R₁, R₂, R₃ and R₄ are each, independently, H,C₁-C₄ alkyl, C₁-C₄ haloalkyl or C₂-C₄ alkoxyalkyl; R₅ is C₁-C₃ alkyl,C₂-C₄ alkenyl, or C₂-C₄ haloalkyl; R₆ is H, halogen, CN, NO₂, C₁-C₄alkyl, C₂-C₄ alkenyl, or C₂-C₄ alkoxyalkyl; X is O or S(O)_(n) n iszero, 1 or 2; Y is CR₇R₈, CHOR₉, C(OR₉)₂, C═NOR₁₀ or C═NNR₂₀R₂₁; R₇ isH, C₁-C₄ alkyl or C₁-C₄ haloalkyl; R₈ is H, C₁-C₄ alkyl or C₂-C₄ alkenylor C₂-C₄ alkynyl; R₉ and R₁₀ are each, independently H or C₁-C₆ alkyloptionally substituted with one or more halogen, C₁-C₄ alkoxy, C₂-C₆alkenyl, C₂-C₆ alkynyl, C₁-C₆ haloalkyl or C₃-C₆ cycloalkyl groups; R₂₀and R₂₁ are each independently H or C₁-C₆ alkyl; Z is H, halogen, C₁-C₄alkyl, C₁-C₄ haloalkyl, C₂-C₄ alkoxyalkyl, C₁-C₄ alkoxy or C₁-C₄haloalkoxy; and p is zero, 1, 2, or 3 which process comprises reacting acompound of formula II

with Lawesson's Reagent in the presence of a solvent.